Small handheld electronic devices, such as palmtop computers, handheld notepads, and handheld organizers, are well known and are increasing in popularity. An example is the Newton manufactured by the Apple Computer Corporation. To provide visually perceptible output to a user, such devices typically employ liquid crystal displays (LCDs). In selecting the size of an LCD for such devices, a balance must be struck between performance and cost.
If an LCD with a capability to display a large number of pixels (e.g. 640.times.480) is used, the display resolution is high and the displayed information is easily readable. However, such devices are expensive, and the associated computer is necessarily fairly bulky. Conversely, an LCD capable of displaying fewer pixels (e.g. 320.times.240) costs less and is smaller, but provides poorer display resolution.
In handheld and portable devices common in the prior art, a one-to-one mapping of memory to LCD is typically used. That is, each pixel in memory corresponds to a pixel on the LCD. This practice ties the size of the LCD to the size of the internal memory. If a smaller LCD is used, then memory size of the device is decreased accordingly, thereby limiting the data storage required.
In accordance with a preferred embodiment of the present invention, the foregoing and additional drawbacks of the prior art are overcome. A relatively large set of input image data (e.g. 640.times.480) is mapped onto a relative smaller physical display device (e.g. 320.times.240) by one of a variety of techniques, each typically characterized by display of a subset of the input data at full resolution (i.e. 1:1). In some embodiments, the entire physical display is dedicated to display of the subset of input data at 1:1 resolution; data beyond this subset is not displayed. In other embodiments, only a portion of the physical display is dedicated to 1:1 resolution, with the remainder of the physical display being used to represent some fraction of the input data outside the 1:1 subset. In one such embodiment, input data around the subset displayed at 1:1 resolution is displayed at another fixed resolution, such as 2:1 (i.e. displaying every other row/column of data). In another such embodiment, the display resolution outside the 1:1 portion gradually fades into 2:1 resolution, 3:1, 4:1, etc. A variety of other alternatives are possible.
Data displayed in these lower resolution portions of the display device is geometrically distorted and/or compressed, but provides useful context information for the user. Desirably, user-responsive control means are provided by which the user can move the 1:1 resolution portion of the window to display different portions of the input data image.
The foregoing and other features and advantages of the preferred embodiment of the present invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.